/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.catalina.session;

import java.beans.PropertyChangeSupport;
import java.io.IOException;
import java.io.NotSerializableException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.lang.reflect.Method;
import java.security.AccessController;
import java.security.Principal;
import java.security.PrivilegedAction;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicInteger;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionActivationListener;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;
import javax.servlet.http.HttpSessionBindingListener;
import javax.servlet.http.HttpSessionContext;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;

import org.apache.catalina.Context;
import org.apache.catalina.Globals;
import org.apache.catalina.Manager;
import org.apache.catalina.Session;
import org.apache.catalina.SessionEvent;
import org.apache.catalina.SessionListener;
import org.apache.catalina.security.SecurityUtil;
import org.apache.catalina.util.Enumerator;
import org.apache.catalina.util.StringManager;

/**
 * Standard implementation of the <b>Session</b> interface. This object is
 * serializable, so that it can be stored in persistent storage or transferred
 * to a different JVM for distributable session support.
 * <p>
 * <b>IMPLEMENTATION NOTE</b>: An instance of this class represents both the
 * internal (Session) and application level (HttpSession) view of the session.
 * However, because the class itself is not declared public, Java logic outside
 * of the <code>org.apache.catalina.session</code> package cannot cast an
 * HttpSession view of this instance back to a Session view.
 * <p>
 * <b>IMPLEMENTATION NOTE</b>: If you add fields to this class, you must make
 * sure that you carry them over in the read/writeObject methods so that this
 * class is properly serialized.
 * 
 * @author Craig R. McClanahan
 * @author Sean Legassick
 * @author <a href="mailto:jon@latchkey.com">Jon S. Stevens</a>
 * @version $Revision: 672012 $ $Date: 2008-06-27 03:48:30 +0800 (星期五, 27 六月
 *          2008) $
 */

public class StandardSession implements HttpSession, Session, Serializable {

	protected static final boolean ACTIVITY_CHECK = Globals.STRICT_SERVLET_COMPLIANCE
			|| Boolean
					.valueOf(
							System
									.getProperty(
											"org.apache.catalina.session.StandardSession.ACTIVITY_CHECK",
											"false")).booleanValue();

	// ----------------------------------------------------------- Constructors

	/**
	 * Construct a new Session associated with the specified Manager.
	 * 
	 * @param manager
	 *            The manager with which this Session is associated
	 */
	public StandardSession(Manager manager) {

		super();
		this.manager = manager;

		// Initialize access count
		if (ACTIVITY_CHECK) {
			accessCount = new AtomicInteger();
		}

	}

	// ----------------------------------------------------- Instance Variables

	/**
	 * Type array.
	 */
	protected static final String EMPTY_ARRAY[] = new String[0];

	/**
	 * The dummy attribute value serialized when a NotSerializableException is
	 * encountered in <code>writeObject()</code>.
	 */
	protected static final String NOT_SERIALIZED = "___NOT_SERIALIZABLE_EXCEPTION___";

	/**
	 * The collection of user data attributes associated with this Session.
	 */
	protected Map attributes = new ConcurrentHashMap();

	/**
	 * The authentication type used to authenticate our cached Principal, if
	 * any. NOTE: This value is not included in the serialized version of this
	 * object.
	 */
	protected transient String authType = null;

	/**
	 * The <code>java.lang.Method</code> for the
	 * <code>fireContainerEvent()</code> method of the
	 * <code>org.apache.catalina.core.StandardContext</code> method, if our
	 * Context implementation is of this class. This value is computed
	 * dynamically the first time it is needed, or after a session reload (since
	 * it is declared transient).
	 */
	protected transient Method containerEventMethod = null;

	/**
	 * The method signature for the <code>fireContainerEvent</code> method.
	 */
	protected static final Class containerEventTypes[] = { String.class,
			Object.class };

	/**
	 * The time this session was created, in milliseconds since midnight,
	 * January 1, 1970 GMT.
	 */
	protected long creationTime = 0L;

	/**
	 * Set of attribute names which are not allowed to be persisted.
	 */
	protected static final String[] excludedAttributes = { Globals.SUBJECT_ATTR };

	/**
	 * We are currently processing a session expiration, so bypass certain
	 * IllegalStateException tests. NOTE: This value is not included in the
	 * serialized version of this object.
	 */
	protected transient boolean expiring = false;

	/**
	 * The facade associated with this session. NOTE: This value is not included
	 * in the serialized version of this object.
	 */
	protected transient StandardSessionFacade facade = null;

	/**
	 * The session identifier of this Session.
	 */
	protected String id = null;

	/**
	 * Descriptive information describing this Session implementation.
	 */
	protected static final String info = "StandardSession/1.0";

	/**
	 * The last accessed time for this Session.
	 */
	protected long lastAccessedTime = creationTime;

	/**
	 * The session event listeners for this Session.
	 */
	protected transient ArrayList listeners = new ArrayList();

	/**
	 * The Manager with which this Session is associated.
	 */
	protected transient Manager manager = null;

	/**
	 * The maximum time interval, in seconds, between client requests before the
	 * servlet container may invalidate this session. A negative time indicates
	 * that the session should never time out.
	 */
	protected int maxInactiveInterval = -1;

	/**
	 * Flag indicating whether this session is new or not.
	 */
	protected boolean isNew = false;

	/**
	 * Flag indicating whether this session is valid or not.
	 */
	protected boolean isValid = false;

	/**
	 * Internal notes associated with this session by Catalina components and
	 * event listeners. <b>IMPLEMENTATION NOTE:</b> This object is <em>not</em>
	 * saved and restored across session serializations!
	 */
	protected transient Map notes = new Hashtable();

	/**
	 * The authenticated Principal associated with this session, if any.
	 * <b>IMPLEMENTATION NOTE:</b> This object is <i>not</i> saved and
	 * restored across session serializations!
	 */
	protected transient Principal principal = null;

	/**
	 * The string manager for this package.
	 */
	protected static StringManager sm = StringManager
			.getManager(Constants.Package);

	/**
	 * The HTTP session context associated with this session.
	 */
	protected static HttpSessionContext sessionContext = null;

	/**
	 * The property change support for this component. NOTE: This value is not
	 * included in the serialized version of this object.
	 */
	protected transient PropertyChangeSupport support = new PropertyChangeSupport(
			this);

	/**
	 * The current accessed time for this session.
	 */
	protected long thisAccessedTime = creationTime;

	/**
	 * The access count for this session.
	 */
	protected transient AtomicInteger accessCount = null;

	// ----------------------------------------------------- Session Properties

	/**
	 * Return the authentication type used to authenticate our cached Principal,
	 * if any.
	 */
	public String getAuthType() {

		return (this.authType);

	}

	/**
	 * Set the authentication type used to authenticate our cached Principal, if
	 * any.
	 * 
	 * @param authType
	 *            The new cached authentication type
	 */
	public void setAuthType(String authType) {

		String oldAuthType = this.authType;
		this.authType = authType;
		support.firePropertyChange("authType", oldAuthType, this.authType);

	}

	/**
	 * Set the creation time for this session. This method is called by the
	 * Manager when an existing Session instance is reused.
	 * 
	 * @param time
	 *            The new creation time
	 */
	public void setCreationTime(long time) {

		this.creationTime = time;
		this.lastAccessedTime = time;
		this.thisAccessedTime = time;

	}

	/**
	 * Return the session identifier for this session.
	 */
	public String getId() {

		return (this.id);

	}

	/**
	 * Return the session identifier for this session.
	 */
	public String getIdInternal() {

		return (this.id);

	}

	/**
	 * Set the session identifier for this session.
	 * 
	 * @param id
	 *            The new session identifier
	 */
	public void setId(String id) {

		if ((this.id != null) && (manager != null))
			manager.remove(this);

		this.id = id;

		if (manager != null)
			manager.add(this);
		tellNew();
	}

	/**
	 * Inform the listeners about the new session.
	 * 
	 */
	public void tellNew() {

		// Notify interested session event listeners
		fireSessionEvent(Session.SESSION_CREATED_EVENT, null);

		// Notify interested application event listeners
		Context context = (Context) manager.getContainer();
		Object listeners[] = context.getApplicationLifecycleListeners();
		if (listeners != null) {
			HttpSessionEvent event = new HttpSessionEvent(getSession());
			for (int i = 0; i < listeners.length; i++) {
				if (!(listeners[i] instanceof HttpSessionListener))
					continue;
				HttpSessionListener listener = (HttpSessionListener) listeners[i];
				try {
					fireContainerEvent(context, "beforeSessionCreated",
							listener);
					listener.sessionCreated(event);
					fireContainerEvent(context, "afterSessionCreated", listener);
				} catch (Throwable t) {
					try {
						fireContainerEvent(context, "afterSessionCreated",
								listener);
					} catch (Exception e) {
						;
					}
					manager.getContainer().getLogger().error(
							sm.getString("standardSession.sessionEvent"), t);
				}
			}
		}

	}

	/**
	 * Return descriptive information about this Session implementation and the
	 * corresponding version number, in the format
	 * <code>&lt;description&gt;/&lt;version&gt;</code>.
	 */
	public String getInfo() {

		return (info);

	}

	/**
	 * Return the last time the client sent a request associated with this
	 * session, as the number of milliseconds since midnight, January 1, 1970
	 * GMT. Actions that your application takes, such as getting or setting a
	 * value associated with the session, do not affect the access time.
	 */
	public long getLastAccessedTime() {

		if (!isValidInternal()) {
			throw new IllegalStateException(sm
					.getString("standardSession.getLastAccessedTime.ise"));
		}

		return (this.lastAccessedTime);
	}

	/**
	 * Return the last client access time without invalidation check
	 * 
	 * @see #getLastAccessedTime().
	 */
	public long getLastAccessedTimeInternal() {
		return (this.lastAccessedTime);
	}

	/**
	 * Return the Manager within which this Session is valid.
	 */
	public Manager getManager() {

		return (this.manager);

	}

	/**
	 * Set the Manager within which this Session is valid.
	 * 
	 * @param manager
	 *            The new Manager
	 */
	public void setManager(Manager manager) {

		this.manager = manager;

	}

	/**
	 * Return the maximum time interval, in seconds, between client requests
	 * before the servlet container will invalidate the session. A negative time
	 * indicates that the session should never time out.
	 */
	public int getMaxInactiveInterval() {

		return (this.maxInactiveInterval);

	}

	/**
	 * Set the maximum time interval, in seconds, between client requests before
	 * the servlet container will invalidate the session. A negative time
	 * indicates that the session should never time out.
	 * 
	 * @param interval
	 *            The new maximum interval
	 */
	public void setMaxInactiveInterval(int interval) {

		this.maxInactiveInterval = interval;
		if (isValid && interval == 0) {
			expire();
		}

	}

	/**
	 * Set the <code>isNew</code> flag for this session.
	 * 
	 * @param isNew
	 *            The new value for the <code>isNew</code> flag
	 */
	public void setNew(boolean isNew) {

		this.isNew = isNew;

	}

	/**
	 * Return the authenticated Principal that is associated with this Session.
	 * This provides an <code>Authenticator</code> with a means to cache a
	 * previously authenticated Principal, and avoid potentially expensive
	 * <code>Realm.authenticate()</code> calls on every request. If there is
	 * no current associated Principal, return <code>null</code>.
	 */
	public Principal getPrincipal() {

		return (this.principal);

	}

	/**
	 * Set the authenticated Principal that is associated with this Session.
	 * This provides an <code>Authenticator</code> with a means to cache a
	 * previously authenticated Principal, and avoid potentially expensive
	 * <code>Realm.authenticate()</code> calls on every request.
	 * 
	 * @param principal
	 *            The new Principal, or <code>null</code> if none
	 */
	public void setPrincipal(Principal principal) {

		Principal oldPrincipal = this.principal;
		this.principal = principal;
		support.firePropertyChange("principal", oldPrincipal, this.principal);

	}

	/**
	 * Return the <code>HttpSession</code> for which this object is the
	 * facade.
	 */
	public HttpSession getSession() {

		if (facade == null) {
			if (SecurityUtil.isPackageProtectionEnabled()) {
				final StandardSession fsession = this;
				facade = (StandardSessionFacade) AccessController
						.doPrivileged(new PrivilegedAction() {
							public Object run() {
								return new StandardSessionFacade(fsession);
							}
						});
			} else {
				facade = new StandardSessionFacade(this);
			}
		}
		return (facade);

	}

	/**
	 * Return the <code>isValid</code> flag for this session.
	 */
	public boolean isValid() {

		if (this.expiring) {
			return true;
		}

		if (!this.isValid) {
			return false;
		}

		if (ACTIVITY_CHECK && accessCount.get() > 0) {
			return true;
		}

		if (maxInactiveInterval >= 0) {
			long timeNow = System.currentTimeMillis();
			int timeIdle = (int) ((timeNow - thisAccessedTime) / 1000L);
			if (timeIdle >= maxInactiveInterval) {
				expire(true);
			}
		}

		return (this.isValid);
	}

	/**
	 * Set the <code>isValid</code> flag for this session.
	 * 
	 * @param isValid
	 *            The new value for the <code>isValid</code> flag
	 */
	public void setValid(boolean isValid) {
		this.isValid = isValid;
	}

	// ------------------------------------------------- Session Public Methods

	/**
	 * Update the accessed time information for this session. This method should
	 * be called by the context when a request comes in for a particular
	 * session, even if the application does not reference it.
	 */
	public void access() {

		this.lastAccessedTime = this.thisAccessedTime;
		this.thisAccessedTime = System.currentTimeMillis();

		if (ACTIVITY_CHECK) {
			accessCount.incrementAndGet();
		}

	}

	/**
	 * End the access.
	 */
	public void endAccess() {

		isNew = false;

		if (ACTIVITY_CHECK) {
			accessCount.decrementAndGet();
		}

	}

	/**
	 * Add a session event listener to this component.
	 */
	public void addSessionListener(SessionListener listener) {

		listeners.add(listener);

	}

	/**
	 * Perform the internal processing required to invalidate this session,
	 * without triggering an exception if the session has already expired.
	 */
	public void expire() {

		expire(true);

	}

	/**
	 * Perform the internal processing required to invalidate this session,
	 * without triggering an exception if the session has already expired.
	 * 
	 * @param notify
	 *            Should we notify listeners about the demise of this session?
	 */
	public void expire(boolean notify) {

		// Mark this session as "being expired" if needed
		if (expiring)
			return;

		synchronized (this) {

			if (manager == null)
				return;

			expiring = true;

			// Notify interested application event listeners
			// FIXME - Assumes we call listeners in reverse order
			Context context = (Context) manager.getContainer();
			Object listeners[] = context.getApplicationLifecycleListeners();
			if (notify && (listeners != null)) {
				HttpSessionEvent event = new HttpSessionEvent(getSession());
				for (int i = 0; i < listeners.length; i++) {
					int j = (listeners.length - 1) - i;
					if (!(listeners[j] instanceof HttpSessionListener))
						continue;
					HttpSessionListener listener = (HttpSessionListener) listeners[j];
					try {
						fireContainerEvent(context, "beforeSessionDestroyed",
								listener);
						listener.sessionDestroyed(event);
						fireContainerEvent(context, "afterSessionDestroyed",
								listener);
					} catch (Throwable t) {
						try {
							fireContainerEvent(context,
									"afterSessionDestroyed", listener);
						} catch (Exception e) {
							;
						}
						manager
								.getContainer()
								.getLogger()
								.error(
										sm
												.getString("standardSession.sessionEvent"),
										t);
					}
				}
			}
			if (ACTIVITY_CHECK) {
				accessCount.set(0);
			}
			setValid(false);

			/*
			 * Compute how long this session has been alive, and update session
			 * manager's related properties accordingly
			 */
			long timeNow = System.currentTimeMillis();
			int timeAlive = (int) ((timeNow - creationTime) / 1000);
			synchronized (manager) {
				if (timeAlive > manager.getSessionMaxAliveTime()) {
					manager.setSessionMaxAliveTime(timeAlive);
				}
				int numExpired = manager.getExpiredSessions();
				numExpired++;
				manager.setExpiredSessions(numExpired);
				int average = manager.getSessionAverageAliveTime();
				average = ((average * (numExpired - 1)) + timeAlive)
						/ numExpired;
				manager.setSessionAverageAliveTime(average);
			}

			// Remove this session from our manager's active sessions
			manager.remove(this);

			// Notify interested session event listeners
			if (notify) {
				fireSessionEvent(Session.SESSION_DESTROYED_EVENT, null);
			}

			// We have completed expire of this session
			expiring = false;

			// Unbind any objects associated with this session
			String keys[] = keys();
			for (int i = 0; i < keys.length; i++)
				removeAttributeInternal(keys[i], notify);

		}

	}

	/**
	 * Perform the internal processing required to passivate this session.
	 */
	public void passivate() {

		// Notify interested session event listeners
		fireSessionEvent(Session.SESSION_PASSIVATED_EVENT, null);

		// Notify ActivationListeners
		HttpSessionEvent event = null;
		String keys[] = keys();
		for (int i = 0; i < keys.length; i++) {
			Object attribute = attributes.get(keys[i]);
			if (attribute instanceof HttpSessionActivationListener) {
				if (event == null)
					event = new HttpSessionEvent(getSession());
				try {
					((HttpSessionActivationListener) attribute)
							.sessionWillPassivate(event);
				} catch (Throwable t) {
					manager.getContainer().getLogger().error(
							sm.getString("standardSession.attributeEvent"), t);
				}
			}
		}

	}

	/**
	 * Perform internal processing required to activate this session.
	 */
	public void activate() {

		// Initialize access count
		if (ACTIVITY_CHECK) {
			accessCount = new AtomicInteger();
		}

		// Notify interested session event listeners
		fireSessionEvent(Session.SESSION_ACTIVATED_EVENT, null);

		// Notify ActivationListeners
		HttpSessionEvent event = null;
		String keys[] = keys();
		for (int i = 0; i < keys.length; i++) {
			Object attribute = attributes.get(keys[i]);
			if (attribute instanceof HttpSessionActivationListener) {
				if (event == null)
					event = new HttpSessionEvent(getSession());
				try {
					((HttpSessionActivationListener) attribute)
							.sessionDidActivate(event);
				} catch (Throwable t) {
					manager.getContainer().getLogger().error(
							sm.getString("standardSession.attributeEvent"), t);
				}
			}
		}

	}

	/**
	 * Return the object bound with the specified name to the internal notes for
	 * this session, or <code>null</code> if no such binding exists.
	 * 
	 * @param name
	 *            Name of the note to be returned
	 */
	public Object getNote(String name) {

		return (notes.get(name));

	}

	/**
	 * Return an Iterator containing the String names of all notes bindings that
	 * exist for this session.
	 */
	public Iterator getNoteNames() {

		return (notes.keySet().iterator());

	}

	/**
	 * Release all object references, and initialize instance variables, in
	 * preparation for reuse of this object.
	 */
	public void recycle() {

		// Reset the instance variables associated with this Session
		attributes.clear();
		setAuthType(null);
		creationTime = 0L;
		expiring = false;
		id = null;
		lastAccessedTime = 0L;
		maxInactiveInterval = -1;
		notes.clear();
		setPrincipal(null);
		isNew = false;
		isValid = false;
		manager = null;

	}

	/**
	 * Remove any object bound to the specified name in the internal notes for
	 * this session.
	 * 
	 * @param name
	 *            Name of the note to be removed
	 */
	public void removeNote(String name) {

		notes.remove(name);

	}

	/**
	 * Remove a session event listener from this component.
	 */
	public void removeSessionListener(SessionListener listener) {

		listeners.remove(listener);

	}

	/**
	 * Bind an object to a specified name in the internal notes associated with
	 * this session, replacing any existing binding for this name.
	 * 
	 * @param name
	 *            Name to which the object should be bound
	 * @param value
	 *            Object to be bound to the specified name
	 */
	public void setNote(String name, Object value) {

		notes.put(name, value);

	}

	/**
	 * Return a string representation of this object.
	 */
	public String toString() {

		StringBuffer sb = new StringBuffer();
		sb.append("StandardSession[");
		sb.append(id);
		sb.append("]");
		return (sb.toString());

	}

	// ------------------------------------------------ Session Package Methods

	/**
	 * Read a serialized version of the contents of this session object from the
	 * specified object input stream, without requiring that the StandardSession
	 * itself have been serialized.
	 * 
	 * @param stream
	 *            The object input stream to read from
	 * 
	 * @exception ClassNotFoundException
	 *                if an unknown class is specified
	 * @exception IOException
	 *                if an input/output error occurs
	 */
	public void readObjectData(ObjectInputStream stream)
			throws ClassNotFoundException, IOException {

		readObject(stream);

	}

	/**
	 * Write a serialized version of the contents of this session object to the
	 * specified object output stream, without requiring that the
	 * StandardSession itself have been serialized.
	 * 
	 * @param stream
	 *            The object output stream to write to
	 * 
	 * @exception IOException
	 *                if an input/output error occurs
	 */
	public void writeObjectData(ObjectOutputStream stream) throws IOException {

		writeObject(stream);

	}

	// ------------------------------------------------- HttpSession Properties

	/**
	 * Return the time when this session was created, in milliseconds since
	 * midnight, January 1, 1970 GMT.
	 * 
	 * @exception IllegalStateException
	 *                if this method is called on an invalidated session
	 */
	public long getCreationTime() {

		if (!isValidInternal())
			throw new IllegalStateException(sm
					.getString("standardSession.getCreationTime.ise"));

		return (this.creationTime);

	}

	/**
	 * Return the ServletContext to which this session belongs.
	 */
	public ServletContext getServletContext() {

		if (manager == null)
			return (null);
		Context context = (Context) manager.getContainer();
		if (context == null)
			return (null);
		else
			return (context.getServletContext());

	}

	/**
	 * Return the session context with which this session is associated.
	 * 
	 * @deprecated As of Version 2.1, this method is deprecated and has no
	 *             replacement. It will be removed in a future version of the
	 *             Java Servlet API.
	 */
	public HttpSessionContext getSessionContext() {

		if (sessionContext == null)
			sessionContext = new StandardSessionContext();
		return (sessionContext);

	}

	// ----------------------------------------------HttpSession Public Methods

	/**
	 * Return the object bound with the specified name in this session, or
	 * <code>null</code> if no object is bound with that name.
	 * 
	 * @param name
	 *            Name of the attribute to be returned
	 * 
	 * @exception IllegalStateException
	 *                if this method is called on an invalidated session
	 */
	public Object getAttribute(String name) {

		if (!isValidInternal())
			throw new IllegalStateException(sm
					.getString("standardSession.getAttribute.ise"));

		if (name == null)
			return null;

		return (attributes.get(name));

	}

	/**
	 * Return an <code>Enumeration</code> of <code>String</code> objects
	 * containing the names of the objects bound to this session.
	 * 
	 * @exception IllegalStateException
	 *                if this method is called on an invalidated session
	 */
	public Enumeration getAttributeNames() {

		if (!isValidInternal())
			throw new IllegalStateException(sm
					.getString("standardSession.getAttributeNames.ise"));

		return (new Enumerator(attributes.keySet(), true));

	}

	/**
	 * Return the object bound with the specified name in this session, or
	 * <code>null</code> if no object is bound with that name.
	 * 
	 * @param name
	 *            Name of the value to be returned
	 * 
	 * @exception IllegalStateException
	 *                if this method is called on an invalidated session
	 * 
	 * @deprecated As of Version 2.2, this method is replaced by
	 *             <code>getAttribute()</code>
	 */
	public Object getValue(String name) {

		return (getAttribute(name));

	}

	/**
	 * Return the set of names of objects bound to this session. If there are no
	 * such objects, a zero-length array is returned.
	 * 
	 * @exception IllegalStateException
	 *                if this method is called on an invalidated session
	 * 
	 * @deprecated As of Version 2.2, this method is replaced by
	 *             <code>getAttributeNames()</code>
	 */
	public String[] getValueNames() {

		if (!isValidInternal())
			throw new IllegalStateException(sm
					.getString("standardSession.getValueNames.ise"));

		return (keys());

	}

	/**
	 * Invalidates this session and unbinds any objects bound to it.
	 * 
	 * @exception IllegalStateException
	 *                if this method is called on an invalidated session
	 */
	public void invalidate() {

		if (!isValidInternal())
			throw new IllegalStateException(sm
					.getString("standardSession.invalidate.ise"));

		// Cause this session to expire
		expire();

	}

	/**
	 * Return <code>true</code> if the client does not yet know about the
	 * session, or if the client chooses not to join the session. For example,
	 * if the server used only cookie-based sessions, and the client has
	 * disabled the use of cookies, then a session would be new on each request.
	 * 
	 * @exception IllegalStateException
	 *                if this method is called on an invalidated session
	 */
	public boolean isNew() {

		if (!isValidInternal())
			throw new IllegalStateException(sm
					.getString("standardSession.isNew.ise"));

		return (this.isNew);

	}

	/**
	 * Bind an object to this session, using the specified name. If an object of
	 * the same name is already bound to this session, the object is replaced.
	 * <p>
	 * After this method executes, and if the object implements
	 * <code>HttpSessionBindingListener</code>, the container calls
	 * <code>valueBound()</code> on the object.
	 * 
	 * @param name
	 *            Name to which the object is bound, cannot be null
	 * @param value
	 *            Object to be bound, cannot be null
	 * 
	 * @exception IllegalStateException
	 *                if this method is called on an invalidated session
	 * 
	 * @deprecated As of Version 2.2, this method is replaced by
	 *             <code>setAttribute()</code>
	 */
	public void putValue(String name, Object value) {

		setAttribute(name, value);

	}

	/**
	 * Remove the object bound with the specified name from this session. If the
	 * session does not have an object bound with this name, this method does
	 * nothing.
	 * <p>
	 * After this method executes, and if the object implements
	 * <code>HttpSessionBindingListener</code>, the container calls
	 * <code>valueUnbound()</code> on the object.
	 * 
	 * @param name
	 *            Name of the object to remove from this session.
	 * 
	 * @exception IllegalStateException
	 *                if this method is called on an invalidated session
	 */
	public void removeAttribute(String name) {

		removeAttribute(name, true);

	}

	/**
	 * Remove the object bound with the specified name from this session. If the
	 * session does not have an object bound with this name, this method does
	 * nothing.
	 * <p>
	 * After this method executes, and if the object implements
	 * <code>HttpSessionBindingListener</code>, the container calls
	 * <code>valueUnbound()</code> on the object.
	 * 
	 * @param name
	 *            Name of the object to remove from this session.
	 * @param notify
	 *            Should we notify interested listeners that this attribute is
	 *            being removed?
	 * 
	 * @exception IllegalStateException
	 *                if this method is called on an invalidated session
	 */
	public void removeAttribute(String name, boolean notify) {

		// Validate our current state
		if (!isValidInternal())
			throw new IllegalStateException(sm
					.getString("standardSession.removeAttribute.ise"));

		removeAttributeInternal(name, notify);

	}

	/**
	 * Remove the object bound with the specified name from this session. If the
	 * session does not have an object bound with this name, this method does
	 * nothing.
	 * <p>
	 * After this method executes, and if the object implements
	 * <code>HttpSessionBindingListener</code>, the container calls
	 * <code>valueUnbound()</code> on the object.
	 * 
	 * @param name
	 *            Name of the object to remove from this session.
	 * 
	 * @exception IllegalStateException
	 *                if this method is called on an invalidated session
	 * 
	 * @deprecated As of Version 2.2, this method is replaced by
	 *             <code>removeAttribute()</code>
	 */
	public void removeValue(String name) {

		removeAttribute(name);

	}

	/**
	 * Bind an object to this session, using the specified name. If an object of
	 * the same name is already bound to this session, the object is replaced.
	 * <p>
	 * After this method executes, and if the object implements
	 * <code>HttpSessionBindingListener</code>, the container calls
	 * <code>valueBound()</code> on the object.
	 * 
	 * @param name
	 *            Name to which the object is bound, cannot be null
	 * @param value
	 *            Object to be bound, cannot be null
	 * 
	 * @exception IllegalArgumentException
	 *                if an attempt is made to add a non-serializable object in
	 *                an environment marked distributable.
	 * @exception IllegalStateException
	 *                if this method is called on an invalidated session
	 */
	public void setAttribute(String name, Object value) {
		setAttribute(name, value, true);
	}

	/**
	 * Bind an object to this session, using the specified name. If an object of
	 * the same name is already bound to this session, the object is replaced.
	 * <p>
	 * After this method executes, and if the object implements
	 * <code>HttpSessionBindingListener</code>, the container calls
	 * <code>valueBound()</code> on the object.
	 * 
	 * @param name
	 *            Name to which the object is bound, cannot be null
	 * @param value
	 *            Object to be bound, cannot be null
	 * @param notify
	 *            whether to notify session listeners
	 * @exception IllegalArgumentException
	 *                if an attempt is made to add a non-serializable object in
	 *                an environment marked distributable.
	 * @exception IllegalStateException
	 *                if this method is called on an invalidated session
	 */

	public void setAttribute(String name, Object value, boolean notify) {

		// Name cannot be null
		if (name == null)
			throw new IllegalArgumentException(sm
					.getString("standardSession.setAttribute.namenull"));

		// Null value is the same as removeAttribute()
		if (value == null) {
			removeAttribute(name);
			return;
		}

		// Validate our current state
		if (!isValidInternal())
			throw new IllegalStateException(sm
					.getString("standardSession.setAttribute.ise"));
		if ((manager != null) && manager.getDistributable()
				&& !(value instanceof Serializable))
			throw new IllegalArgumentException(sm
					.getString("standardSession.setAttribute.iae"));

		// Construct an event with the new value
		HttpSessionBindingEvent event = null;

		// Call the valueBound() method if necessary
		if (notify && value instanceof HttpSessionBindingListener) {
			// Don't call any notification if replacing with the same value
			Object oldValue = attributes.get(name);
			if (value != oldValue) {
				event = new HttpSessionBindingEvent(getSession(), name, value);
				try {
					((HttpSessionBindingListener) value).valueBound(event);
				} catch (Throwable t) {
					manager.getContainer().getLogger().error(
							sm.getString("standardSession.bindingEvent"), t);
				}
			}
		}

		// Replace or add this attribute
		Object unbound = attributes.put(name, value);

		// Call the valueUnbound() method if necessary
		if (notify && (unbound != null) && (unbound != value)
				&& (unbound instanceof HttpSessionBindingListener)) {
			try {
				((HttpSessionBindingListener) unbound)
						.valueUnbound(new HttpSessionBindingEvent(getSession(),
								name));
			} catch (Throwable t) {
				manager.getContainer().getLogger().error(
						sm.getString("standardSession.bindingEvent"), t);
			}
		}

		if (!notify)
			return;

		// Notify interested application event listeners
		Context context = (Context) manager.getContainer();
		Object listeners[] = context.getApplicationEventListeners();
		if (listeners == null)
			return;
		for (int i = 0; i < listeners.length; i++) {
			if (!(listeners[i] instanceof HttpSessionAttributeListener))
				continue;
			HttpSessionAttributeListener listener = (HttpSessionAttributeListener) listeners[i];
			try {
				if (unbound != null) {
					fireContainerEvent(context,
							"beforeSessionAttributeReplaced", listener);
					if (event == null) {
						event = new HttpSessionBindingEvent(getSession(), name,
								unbound);
					}
					listener.attributeReplaced(event);
					fireContainerEvent(context,
							"afterSessionAttributeReplaced", listener);
				} else {
					fireContainerEvent(context, "beforeSessionAttributeAdded",
							listener);
					if (event == null) {
						event = new HttpSessionBindingEvent(getSession(), name,
								value);
					}
					listener.attributeAdded(event);
					fireContainerEvent(context, "afterSessionAttributeAdded",
							listener);
				}
			} catch (Throwable t) {
				try {
					if (unbound != null) {
						fireContainerEvent(context,
								"afterSessionAttributeReplaced", listener);
					} else {
						fireContainerEvent(context,
								"afterSessionAttributeAdded", listener);
					}
				} catch (Exception e) {
					;
				}
				manager.getContainer().getLogger().error(
						sm.getString("standardSession.attributeEvent"), t);
			}
		}

	}

	// ------------------------------------------ HttpSession Protected Methods

	/**
	 * Return the <code>isValid</code> flag for this session without any
	 * expiration check.
	 */
	protected boolean isValidInternal() {
		return (this.isValid || this.expiring);
	}

	/**
	 * Read a serialized version of this session object from the specified
	 * object input stream.
	 * <p>
	 * <b>IMPLEMENTATION NOTE</b>: The reference to the owning Manager is not
	 * restored by this method, and must be set explicitly.
	 * 
	 * @param stream
	 *            The input stream to read from
	 * 
	 * @exception ClassNotFoundException
	 *                if an unknown class is specified
	 * @exception IOException
	 *                if an input/output error occurs
	 */
	protected void readObject(ObjectInputStream stream)
			throws ClassNotFoundException, IOException {

		// Deserialize the scalar instance variables (except Manager)
		authType = null; // Transient only
		creationTime = ((Long) stream.readObject()).longValue();
		lastAccessedTime = ((Long) stream.readObject()).longValue();
		maxInactiveInterval = ((Integer) stream.readObject()).intValue();
		isNew = ((Boolean) stream.readObject()).booleanValue();
		isValid = ((Boolean) stream.readObject()).booleanValue();
		thisAccessedTime = ((Long) stream.readObject()).longValue();
		principal = null; // Transient only
		// setId((String) stream.readObject());
		id = (String) stream.readObject();
		if (manager.getContainer().getLogger().isDebugEnabled())
			manager.getContainer().getLogger().debug(
					"readObject() loading session " + id);

		// Deserialize the attribute count and attribute values
		if (attributes == null)
			attributes = new Hashtable();
		int n = ((Integer) stream.readObject()).intValue();
		boolean isValidSave = isValid;
		isValid = true;
		for (int i = 0; i < n; i++) {
			String name = (String) stream.readObject();
			Object value = (Object) stream.readObject();
			if ((value instanceof String) && (value.equals(NOT_SERIALIZED)))
				continue;
			if (manager.getContainer().getLogger().isDebugEnabled())
				manager.getContainer().getLogger().debug(
						"  loading attribute '" + name + "' with value '"
								+ value + "'");
			attributes.put(name, value);
		}
		isValid = isValidSave;

		if (listeners == null) {
			listeners = new ArrayList();
		}

		if (notes == null) {
			notes = new Hashtable();
		}
	}

	/**
	 * Write a serialized version of this session object to the specified object
	 * output stream.
	 * <p>
	 * <b>IMPLEMENTATION NOTE</b>: The owning Manager will not be stored in the
	 * serialized representation of this Session. After calling
	 * <code>readObject()</code>, you must set the associated Manager
	 * explicitly.
	 * <p>
	 * <b>IMPLEMENTATION NOTE</b>: Any attribute that is not Serializable will
	 * be unbound from the session, with appropriate actions if it implements
	 * HttpSessionBindingListener. If you do not want any such attributes, be
	 * sure the <code>distributable</code> property of the associated Manager
	 * is set to <code>true</code>.
	 * 
	 * @param stream
	 *            The output stream to write to
	 * 
	 * @exception IOException
	 *                if an input/output error occurs
	 */
	protected void writeObject(ObjectOutputStream stream) throws IOException {

		// Write the scalar instance variables (except Manager)
		stream.writeObject(new Long(creationTime));
		stream.writeObject(new Long(lastAccessedTime));
		stream.writeObject(new Integer(maxInactiveInterval));
		stream.writeObject(new Boolean(isNew));
		stream.writeObject(new Boolean(isValid));
		stream.writeObject(new Long(thisAccessedTime));
		stream.writeObject(id);
		if (manager.getContainer().getLogger().isDebugEnabled())
			manager.getContainer().getLogger().debug(
					"writeObject() storing session " + id);

		// Accumulate the names of serializable and non-serializable attributes
		String keys[] = keys();
		ArrayList saveNames = new ArrayList();
		ArrayList saveValues = new ArrayList();
		for (int i = 0; i < keys.length; i++) {
			Object value = attributes.get(keys[i]);
			if (value == null)
				continue;
			else if ((value instanceof Serializable) && (!exclude(keys[i]))) {
				saveNames.add(keys[i]);
				saveValues.add(value);
			} else {
				removeAttributeInternal(keys[i], true);
			}
		}

		// Serialize the attribute count and the Serializable attributes
		int n = saveNames.size();
		stream.writeObject(new Integer(n));
		for (int i = 0; i < n; i++) {
			stream.writeObject((String) saveNames.get(i));
			try {
				stream.writeObject(saveValues.get(i));
				if (manager.getContainer().getLogger().isDebugEnabled())
					manager.getContainer().getLogger().debug(
							"  storing attribute '" + saveNames.get(i)
									+ "' with value '" + saveValues.get(i)
									+ "'");
			} catch (NotSerializableException e) {
				manager.getContainer().getLogger().warn(
						sm.getString("standardSession.notSerializable",
								saveNames.get(i), id), e);
				stream.writeObject(NOT_SERIALIZED);
				if (manager.getContainer().getLogger().isDebugEnabled())
					manager.getContainer().getLogger().debug(
							"  storing attribute '" + saveNames.get(i)
									+ "' with value NOT_SERIALIZED");
			}
		}

	}

	/**
	 * Exclude attribute that cannot be serialized.
	 * 
	 * @param name
	 *            the attribute's name
	 */
	protected boolean exclude(String name) {

		for (int i = 0; i < excludedAttributes.length; i++) {
			if (name.equalsIgnoreCase(excludedAttributes[i]))
				return true;
		}

		return false;
	}

	// ------------------------------------------------------ Protected Methods

	/**
	 * Fire container events if the Context implementation is the
	 * <code>org.apache.catalina.core.StandardContext</code>.
	 * 
	 * @param context
	 *            Context for which to fire events
	 * @param type
	 *            Event type
	 * @param data
	 *            Event data
	 * 
	 * @exception Exception
	 *                occurred during event firing
	 */
	protected void fireContainerEvent(Context context, String type, Object data)
			throws Exception {

		if (!"org.apache.catalina.core.StandardContext".equals(context
				.getClass().getName())) {
			return; // Container events are not supported
		}
		// NOTE: Race condition is harmless, so do not synchronize
		if (containerEventMethod == null) {
			containerEventMethod = context.getClass().getMethod(
					"fireContainerEvent", containerEventTypes);
		}
		Object containerEventParams[] = new Object[2];
		containerEventParams[0] = type;
		containerEventParams[1] = data;
		containerEventMethod.invoke(context, containerEventParams);

	}

	/**
	 * Notify all session event listeners that a particular event has occurred
	 * for this Session. The default implementation performs this notification
	 * synchronously using the calling thread.
	 * 
	 * @param type
	 *            Event type
	 * @param data
	 *            Event data
	 */
	public void fireSessionEvent(String type, Object data) {
		if (listeners.size() < 1)
			return;
		SessionEvent event = new SessionEvent(this, type, data);
		SessionListener list[] = new SessionListener[0];
		synchronized (listeners) {
			list = (SessionListener[]) listeners.toArray(list);
		}

		for (int i = 0; i < list.length; i++) {
			((SessionListener) list[i]).sessionEvent(event);
		}

	}

	/**
	 * Return the names of all currently defined session attributes as an array
	 * of Strings. If there are no defined attributes, a zero-length array is
	 * returned.
	 */
	protected String[] keys() {

		return ((String[]) attributes.keySet().toArray(EMPTY_ARRAY));

	}

	/**
	 * Remove the object bound with the specified name from this session. If the
	 * session does not have an object bound with this name, this method does
	 * nothing.
	 * <p>
	 * After this method executes, and if the object implements
	 * <code>HttpSessionBindingListener</code>, the container calls
	 * <code>valueUnbound()</code> on the object.
	 * 
	 * @param name
	 *            Name of the object to remove from this session.
	 * @param notify
	 *            Should we notify interested listeners that this attribute is
	 *            being removed?
	 */
	protected void removeAttributeInternal(String name, boolean notify) {

		// Avoid NPE
		if (name == null)
			return;

		// Remove this attribute from our collection
		Object value = attributes.remove(name);

		// Do we need to do valueUnbound() and attributeRemoved() notification?
		if (!notify || (value == null)) {
			return;
		}

		// Call the valueUnbound() method if necessary
		HttpSessionBindingEvent event = null;
		if (value instanceof HttpSessionBindingListener) {
			event = new HttpSessionBindingEvent(getSession(), name, value);
			((HttpSessionBindingListener) value).valueUnbound(event);
		}

		// Notify interested application event listeners
		Context context = (Context) manager.getContainer();
		Object listeners[] = context.getApplicationEventListeners();
		if (listeners == null)
			return;
		for (int i = 0; i < listeners.length; i++) {
			if (!(listeners[i] instanceof HttpSessionAttributeListener))
				continue;
			HttpSessionAttributeListener listener = (HttpSessionAttributeListener) listeners[i];
			try {
				fireContainerEvent(context, "beforeSessionAttributeRemoved",
						listener);
				if (event == null) {
					event = new HttpSessionBindingEvent(getSession(), name,
							value);
				}
				listener.attributeRemoved(event);
				fireContainerEvent(context, "afterSessionAttributeRemoved",
						listener);
			} catch (Throwable t) {
				try {
					fireContainerEvent(context, "afterSessionAttributeRemoved",
							listener);
				} catch (Exception e) {
					;
				}
				manager.getContainer().getLogger().error(
						sm.getString("standardSession.attributeEvent"), t);
			}
		}

	}

}

// ------------------------------------------------------------ Protected Class

/**
 * This class is a dummy implementation of the <code>HttpSessionContext</code>
 * interface, to conform to the requirement that such an object be returned when
 * <code>HttpSession.getSessionContext()</code> is called.
 * 
 * @author Craig R. McClanahan
 * 
 * @deprecated As of Java Servlet API 2.1 with no replacement. The interface
 *             will be removed in a future version of this API.
 */

final class StandardSessionContext implements HttpSessionContext {

	protected HashMap dummy = new HashMap();

	/**
	 * Return the session identifiers of all sessions defined within this
	 * context.
	 * 
	 * @deprecated As of Java Servlet API 2.1 with no replacement. This method
	 *             must return an empty <code>Enumeration</code> and will be
	 *             removed in a future version of the API.
	 */
	public Enumeration getIds() {

		return (new Enumerator(dummy));

	}

	/**
	 * Return the <code>HttpSession</code> associated with the specified
	 * session identifier.
	 * 
	 * @param id
	 *            Session identifier for which to look up a session
	 * 
	 * @deprecated As of Java Servlet API 2.1 with no replacement. This method
	 *             must return null and will be removed in a future version of
	 *             the API.
	 */
	public HttpSession getSession(String id) {

		return (null);

	}

}
